If your hair loss has been a slow, gradual thinning at the crown or a receding hairline over months to years — not a sudden shedding event — you’re most likely dealing with androgenetic alopecia, commonly called pattern hair loss. It’s the most common cause of hair loss in both men and women, and unlike the temporary shedding covered in our guide to postpartum and stress-related hair loss, pattern hair loss doesn’t reverse on its own. Understanding the hormone driving it — dihydrotestosterone, or DHT — is the difference between spending money on marketing claims and putting it toward the handful of treatments that actually have trial data behind them.
This article covers what DHT actually does to a hair follicle, and what the randomized controlled trial evidence really shows for minoxidil, the only treatment approved for both men and women. (Part of our complete guide to hair growth and hair loss — see that page for how pattern hair loss fits alongside deficiency-driven and stress-related causes.) This is general information, not medical advice — a dermatologist can confirm your specific diagnosis and the right treatment for you.
What DHT Actually Does to a Hair Follicle
Dihydrotestosterone is a hormone derived from testosterone by the enzyme 5-alpha-reductase. In people genetically predisposed to pattern hair loss, scalp follicles in certain areas (the crown and hairline in men; the crown and part-line in women) carry androgen receptors that are unusually sensitive to DHT. When DHT binds to these receptors, it triggers a miniaturization cascade: each growth cycle, the affected follicle produces a slightly thinner, shorter hair than the last, and the anagen (growth) phase gets progressively shorter. Over years, a follicle that once produced a thick, pigmented terminal hair ends up producing only a fine, colorless vellus hair — or stops producing visible hair altogether.
This is fundamentally different from the shedding process described in our telogen effluvium article: that process pushes healthy follicles into a temporary resting phase, and they recover. DHT-driven miniaturization is a slow, progressive shrinking of the follicle itself, and it doesn’t reverse without intervention — the earlier it’s treated, the more follicles are still salvageable rather than already miniaturized past the point of response.
What the Minoxidil Evidence Actually Shows
Topical minoxidil is the oldest and most-studied over-the-counter treatment for pattern hair loss, and it’s the only one approved for both men and women. It doesn’t block DHT directly — its exact mechanism isn’t fully settled, but it’s thought to work by prolonging the anagen phase and improving blood flow to the follicle, effectively counteracting some of DHT’s shrinking effect rather than stopping DHT from binding in the first place.
A randomized, placebo-controlled trial in men directly compared 5% and 2% topical minoxidil against placebo over 48 weeks. The 5% formulation added 18.6 non-vellus (visible, terminal) hairs in the target area, compared to 12.7 hairs for the 2% formulation — roughly 45% more regrowth with 5% than 2% — and the 5% group also responded faster, with a difference detectable at earlier follow-up points. The tradeoff: 5% minoxidil caused more scalp itching and irritation than 2%, mainly because of its higher concentration of propylene glycol, the liquid vehicle that carries the drug (a factor that matters less with foam formulations, which use a different vehicle).
In women, a separate placebo-controlled trial found 5% minoxidil superior to placebo on all three of the trial’s primary efficacy measures, while 2% minoxidil beat placebo on hair count and investigator-rated assessments but not on women’s own subjective rating of improvement at 48 weeks — a reminder that objective hair counts and how visible the change feels day-to-day don’t always move together.
Two things matter for anyone starting minoxidil: it typically takes 3-6 months of consistent daily use before any visible change appears (an initial, temporary increase in shedding in the first few weeks is common and not a sign of failure — it reflects old telogen hairs being pushed out to make room for new growth), and the gains are only maintained with continued use. Stopping minoxidil returns the follicles to whatever course DHT was already driving them toward, typically within a few months.
Oral and Low-Dose Options
For people who don’t tolerate topical minoxidil well (scalp irritation, or simply the hassle of a twice-daily application), low-dose oral minoxidil has emerged as an alternative, prescribed off-label at doses far below what’s used for its original purpose as a blood pressure medication. A multicenter safety study of 1,404 patients found the most common side effect was hypertrichosis (unwanted hair growth elsewhere on the body, in about 15% of patients), while more serious systemic effects — lightheadedness, fluid retention, rapid heartbeat — were each reported in under 2% of patients, with no life-threatening events recorded and only about 1.2% of patients stopping due to side effects. It’s a reasonably good safety profile, but because it’s a systemic medication rather than a topical one, it should go through a doctor rather than being self-prescribed.
Where Finasteride Fits (Briefly)
Minoxidil doesn’t block DHT production — finasteride does, by inhibiting the 5-alpha-reductase enzyme that converts testosterone into DHT in the first place. It’s a prescription oral medication, approved for men, with substantial trial data: in year-long randomized trials, men on finasteride 1 mg gained roughly 107 to 138 more hairs in a standardized scalp area than the placebo group at one and two years respectively, and longer-term follow-up found a 93% relative reduction in the likelihood of continued visible hair loss compared to placebo over five years. Because it works through a different mechanism than minoxidil (blocking DHT production versus counteracting its effect at the follicle), dermatologists often combine the two for pattern hair loss that doesn’t respond adequately to minoxidil alone — though finasteride carries its own set of possible side effects and isn’t approved for use in women who are or could become pregnant, so it’s a conversation for a doctor, not a self-directed choice.
Newer research is also exploring topical androgen-receptor blockers — drugs designed to block DHT’s effect directly at the scalp without the systemic hormonal exposure of an oral 5-alpha-reductase inhibitor. This is a promising direction, but the evidence base is much newer and thinner than the decades of data behind minoxidil and finasteride, so it’s worth watching rather than acting on yet.
What This Means in Practice
If your hair loss follows the pattern hair loss picture — gradual thinning at the crown, a receding hairline, or a widening part that’s gotten slowly worse over months to years rather than appearing suddenly — topical minoxidil remains the best-evidenced, lowest-barrier place to start, with the understanding that it manages the process rather than curing it and needs to be continued indefinitely to keep its effect. Anyone considering finasteride, oral minoxidil, or newer options should do so with a dermatologist, both to confirm the diagnosis (ruling out the deficiency-driven and stress-related causes covered elsewhere in our complete guide) and to weigh the tradeoffs of a systemic medication against the severity of the hair loss.
Frequently Asked Questions
How do I know if it’s pattern hair loss and not something else?
Pattern hair loss follows a specific distribution — a receding hairline and/or crown thinning in men, and diffuse thinning concentrated at the crown or a widening part in women — and develops gradually over months to years. Diffuse, all-over shedding with a clear starting point points toward telogen effluvium instead, and patchy bald spots point toward alopecia areata. See our guide to sudden hair fall if your pattern doesn’t clearly fit either description.
Does minoxidil work for everyone?
No. Trial response rates are meaningful but not universal — a portion of users see little to no visible regrowth, and response tends to be better the earlier it’s started, before follicles have miniaturized too far. It also generally works better for maintaining existing hair and slowing further loss than for regrowing hair in areas that have been bald for years.
Can women use the same minoxidil as men?
Women can use minoxidil, and it’s FDA-approved for female pattern hair loss, typically at the 2% or 5% concentration (5% is used off-label by many women and dermatologists despite being originally studied and marketed for men, though it carries a higher chance of unwanted facial hair growth as a side effect in women).
Is DHT the same thing that causes hair loss in women?
The same DHT-driven miniaturization process underlies female pattern hair loss, though hormonal, genetic, and follicle-sensitivity factors differ somewhat between men and women, which is part of why female pattern hair loss tends to present as diffuse crown thinning rather than a receding hairline.
